Glass composition



ESQ-96,34 SR can") L aLbLlL \JUJLC jSEARCH new or lno-ri-ri n'r: cnr;MICOIM! VD \JUL-HJXIIUIL. tun ivlluullvu 1\|\ 1 2 3 013 888 less thanabout 0.16, the sum of the percentages of SiO ZrO ,and TiO; lies betweenabout 55 and 68, and the sum Stphane g fg g :ggggPggggi to of thepercentages of SiO;, ZrO TiO B and A1 0 Compagnie de Saint-Gobain,Paris, France hes between about 67 i No D i Fil N0 5, 19 9, S 351 233 5As examples of permissible variation within the com- 37 Claims. (Cl.106-50) This invention relates to a novel glass composition and to glassfibers made therefrom, and particularly relates to a glass compositionhaving a low B 0 content and/or a low content of ZrO and TiO Thisapplication is a continuation-in-part of applications Serial Nos.595,583 and 595,584, both filed July 3, 1956, both now abandoned.

The invention has as one of its objects the provision of a novel glasscomposition having a low speed of devitrification.

Another object of the invention recites in the provision of a glasscomposition having a viscosity in the neighborhood of 1000 poisesbetween 1000 and 1200" C., whereby the material may easily be drawn intofibers.

Yet another object of the invention lies in the provision of a novelglass composition having a low rate of attackability by water.

Still another object of the invention is the provision of a glasscomposition which is advantageously used in the making of glass fibers,the composition being such that only a low temperature is required forits transformation to fibers, such composition having at most a very lowspeed of devitrification at fiber-making temperatures.

A further object of the invention is the provision of a novel article ofmanufacture in the form of glass fibers made of the above-indicatedglass composition.

The above and further objects of the invention and further advantages ofthe glass composition and of glass fibers made therefrom will morereadily appear in the following specification setting forth preferredexamples of the glass composition of the invention.

The glass composition of the present invention consists essentially offrom about 55 to 68% SiO less than 5% E 0 from about 7 to 10% CaO, fromabout 2 to 5% MgO, from about 11 to 14% alkali metal oxides, ZrO and TiOtotaling less than 5%, and a minor amount of A1 0 all percentages beingby weight. In such composition the Slog, B203, CaO, A1203, ZI'OZ, andare of such proportions that the weight ratio MgO/CaO lies between about0.3 and 0.5, the weight ratio CaO/ SiO; is less than about 0.16, the sumof the percent-- ages of S05, ZrO and TiO; lies between about 55 and 68,and the sum of the percentages of SiO ZrO TiO E 0,, and A1 0 liesbetween about 67 and 72. Preferably the MgO content of the compositionlies between 2.8 and 4.5.

The glass of the invention has the following broad range of composition:

Table I Percent by weight SiO 55-68 BaO 0-5 B 0 0-5 ZrO +TiO 0-5 A1 03-9 :Fezog 0-6 CaO 7-10 MgO 2-5 Na O+K O F 0-4 As above indicated, theSiO B 0 CaO, MgO, A1 0 ZrO and TiO of the composition of the inventionhave such proportions that the weight ratio MgO/CaO lies between about0.3 and 0.5, the weight ratio CaO/Si0 is position range set forth inTable I above, there are set forth below in Table II'six illustrativesubordinate ranges of the composition:

Table II 10 Percent by welglit The compositions in columns 1, 2, 3, and4 of Table II above are illustrative of compositions A lying in onesubordinate field within the broad composition set forth in Table I, andthe compositions shown in columns 5 and 6 in Table II above areillustrative of compositions B within another subordinate field of thebroad composition. In the compositions B of columns 5 and 6 of Table II,B 0 is present and there is no TiO -l-ZrO- In the compositions Aillustrated by columns 1 to 4, inclusive, of Table II, on the otherhand, there need be no B 0 present, but there is an effective amount ofZrO -t-Tio The broad range of ZrO +TiO is 0.5-5 (column 1), the combinedpercentage of ZrO and TiO is preferably less than 3.5 (columns 2, 3, and4 of Table II), and in certain preferred composition such sum liesbetween 2.5 and 3.3 (column 3 of Table II).

On occasion, as shown in Table II above, glass compositions inaccordance with the invention may contain a small quantity of fluorine,less than 4%, particularly in cases where they contain'at most only asmall quantity of B 0 The presence of fluorine in the amount indicatedfacilitates maintaining the temperature at which the composition has aviscosity of 1000 poises in the range 1000 to 1200" C.; the fluorinealso maintains the speed of devitrification below the permitted maximumvalue.

Glass compositions in accordance with the invention may also include asmall quantity of BaO, in general less than 5%, in order to reduce theviscosity of the glass. BaO has no appreciable effect upon theattackability of the glass by water and desirably reduces the speed ofdevitrification of the glass, as well as lowering the-upper temperatureof such devitrification.

It has been found particularly advantageous, in compositions having thesub-ranges set forth in columns 5 and 6 of Table II, to maintain thecontent of B 0 between about 3 and 5%, and preferably between 4.3 and4.6%. Such B 0 contents, particularly the latter, allow attainment of asatisfactory viscosity of the glass in the range of working temperaturesconvenient for drawing glass fibers; such B 0 content also limits thetendency to devitrification of the glass.

Glass compositions within the present invention have a speed ofdevitrification which is at most equal to 2 microns per minute. Suchspeed of devitrification corresponds to the greatest speed of growth ofthe crystals in the glass, each glass having a maximum speed ofdevitrification at one definite temperature. Glass gompositions in 1-2Na O+K O 11.5-13. F

BaO

Glass compositions in accordance with the invention 3 may be employed ina number of different manners.

They may advantageously be employed for the manufacture of glass fibersas by use of known centrifugal machines wherein the glass fibers aredrawn or extruded from dies in refractory containers under the influenceof centrifugal force. The glass compositions of the inverb tion areparticularly useful in forming fibers by this method by reason of thecomparatively low temperature which they require for theirtransformation into fibers, and because their speed of devitrificationat the fibre drawing or forming temperature is, for all practicalpurposes, zero. Such glass compositions may also be used to advantage inthe making of molded or pressed glass articles which desirably posses alow attackability by water. Whereas for purposes of illustration I havedisclosed preferred embodiments of the glass composition of the Thesolution is now Table III Such attackability by water is measured bytaking 4 cc. of glass ground so that it passes through a screen having-60 meshes/in. and heating such ground glass for five hours at 100 C. in100 cc. of water.

The resultant weight, expressed as mg. of residue per 100 cc. of water,measures the attackability of the glass by water.

By way of non-limiting examples, the analyses of eleven glasscompositions in accordance with the invention, and

..526l2776803 2 29 53 S56 005556554 V10 6 St e i.9 4 4. O4 i f 5 C O44OOD3I 3I 9 80 00 e M 'm w w 1 .1.1 P 022 a O a I. to 5 1 g t ,St r H"a n 5 1 n fld H h .m i m hnlhe .m 11 "625148708039 fl 9 80 .m H Cn h i fM 10 P n 0 2.18 m0 440003lm031 9 0 9O q pO O 2 06 W a I 1. w d. u nuQm Wnm to r .t .l .1 i mm w u n n w mo mmm mm a t 03 3.33.00.115 .7 2 25 00a t 1 3 4 oat P 0 n W m 0 0 .430 U41 O n 0 91 91 C 9 m W .D m n 0 my n U1 1 8.5 0 r 8 .1 w C e 1n 2m 3 m upnt. PO nto O 1 0 7 0 3 3512 8fi 426 6mm e g ew iw 2 C7 af n 0 .8 5?; .m IIIIaM wa em b n 1 m a ab w u n u u nw u ah wm .i Vd m 3 .Ilb Ot J. 1.1205661116870818 9 G8 S .m 1 n n 00S.1.ldn a i 5 l. 4 6h 6 O HS S a 63 0 04 .44009310 21 0 %0 S C n f C 6 2n C 1 n 1 UUB A O a nu. n, n m n n n n u n n u r an 8 m 3 m0attuoaaihnoain u 80 mm m m e s m mCaaM m mm 1 6 l U a n i mrwoh w m h w030 T953 m007l5 .7 H 5 00 0 e C m n u u u u n M m Z moz ao atfmum n 81mm mfl em u Ss am an 1 L ene-n 0 ah LUW H 3 0 h n t 2 O 2. no 6 0 v w Ofime a mdmdemw b o a aa apmp m w mm .mwad c SBBZFMMNF awTwmwto6 A01117507412010 1 02 m 90 1 1. 1. m 1. m a m e m w a r 0 2357 20111907568G 00 n. 05 n O n r1 n yd H 6555 5 muff .7 5 0 7 4 L2 0 L n ma m Wmmwnmnm mmflmw%bm 0m n 1 1, 1- L U .1 d] 28 .Ui a q mm a w w m we. W w mW 5.3 9a 14 m5 WSOZSBBBDOBG m m5 MW m mfi "m T b m b M y 3 an a 5 1 0 73 L2L1 & 0 90 91 w m m 0 sn o i b 5 U" 1 i s oyg i m eam m CC T Pu 5 O if1 h h 1 0 V hC H 0 elf e1 2 t e 3 31273010605 W 05 55 .h m O HO4 W C Q0.3 .810731l221 0 mwo m n .h H 3 r 5 u u 1 1 1 1 nnme m m hfm eW mh h n.u u" a H e v 5 .0 GF 7 M nm mwim n n u 44 1 1l2730600O3 m m6 wm r w waTafl w w w r we 3 er0 7 3 1 2 2 1 0 80 on m mi o nZ n n 1 1 1 a ae s o rV t t t m m mfi wn mmm m I O 0.1 .1 0 20 00208 00028 NW 3 55 ww b m Cm.Wf 3 d 8 9 QL:R Lus 2 2 3 i 9 90 mm w mw mow mm M n n u u 11 .laatefiu m e a a v mhs .m mm medsfimO m U aw 0 mluqw n S M iwmk n u mmnmmmwnm m nnmmmwmm o I u a t t. l g 1.! C 0 1 um? I .ww mn nmnad ra w w nmmON- 3C O C ddt JM :1 i a o .l t. P f a wm mnm I mm m d w mem w wnwm S cC .l. V. y 9d. th. .3a 3. t n a ma mmnm ms wmmn emm m immm me n u. n Wmms l mm Ousal0 m.m w w O A u lu n5 0 tfi t. 004i 3 O m mmm D a a mSn r suu T mm mmmmm wmm e m do n n mw amw n w w n rmm w h u m 2 6 0 a m w wwmm .5 m w m m m 3% g t l l 2 .1 AD v u PbaP mZ amass ad ch &BZAFCMaccordance with the invention have a viscosity of 1000 poises in thetemperature range 1000 to 1200 C. Further, such glass compositions havean attackability by water, measured according to the standardsestablished by Deutsche Glastechnische Gesellschaft, which is atmostequal to 10 mg.

filtered and the filtrate is evaporated, after which the residue fromthe filtrate is heated to C. and then is weighed.

their properties of attackability by water, devitrification andviscosity, are given in the following table:

3. A glass composition consisting essentially of the following: fromabout 55 to 68% SiO less than 5% B from about 7 to 10% CaO, from about 2to MgO, from about 11 to 14% alkali metal oxides, and a minor amount ofA1 0 all percentages being by weight, the CaO, MgO, SiO and A1 0 havingsuch proportions in the composition that the weight ratio MgO/CaO liesbetween about 0.3 and 0.5, the weight ratio CaO/Si0 is less than about0.16, and the sum of the percentages of SiO;, B 0 and A1 0; lies betweenabout 67 and 72.

4. A glass composition consisting essentially of the following: fromabout 55 to 68% SiO from 3 to 5% E 0 from about 7 to 10% C210, fromabout 2 to 5% MgO, from about 11 to 14% alkali metal oxides, and a minoramount of A1 0 all percentages being by weight, the CaO, MgO, SiO and A10 having such proportions in the composition that the weight ratioMgO/CaO lies between about 0.3 and 0.5, the weight ratio CaO/SiO is lessthan about 0.16, and the sum of the percentages of SiO;, B 0 and A1 0lies between about 67 and 72.

5. A glass composition consisting essentially of the following: fromabout 55 to 68% $0,, from about 4.3 to 4.6% B 0 from about 7 to 10% CaO,from about 2 to 5% MgO, from about 11 to 14% alkali metal oxides, and aminor amount of A1 0 all percentages being by weight, the CaO, MgO, SiOand A1 0 having such proportions in the composition that the weightratio MgO/CaO lies between about 0.3 and 0.5, the weight ratio CaO/SiOis less than about 0.16, and thesum of the percentages of SiO B 0 and A10 lies between about 67 and 72.

6. A glass composition consisting essentially of the following: fromabout 55 to 68% 510;, less than 5% B 0 from about 7 to 10% CaO, fromabout 2.8 to 4.5% MgO, from about 11 to 14% alkali metal oxides, and aminor amount of A1 0 all percentages being by weight, the C210, MgO, SiOand A1 0 having such proportions in the composition that the weightratio MgO/CaO lies between about 0.3 and 0.5, the weight ratio CaO/SiO;is less than about 0.16, and the sum of the percentages of SiO B 0 andA1 0 lies between about 67 and 72.

7. A glass composition consisting essentially of the following: fromabout 55 to 68% SiO less than 5% B 0 from about 7 to 10% CaO, from about2 to 5% MgO, from about 11 to 14% alkali metal oxides, a minor amount ofA1 0 and less than 5% (TiO -l-ZrO all percentages being by weight, theCaO, MgO, SiO and A1 0 having such proportions in the composition thatthe weight ratio MgO/CaO lies between about 0.3 and 0.5, the weightratio CaO/SiO is less than about 0.16, and the sum of the percentages ofSiO;, B 0 and A1 0 lies between about 67 and 72.

8. A glass composition consisting essentially of the following: fromabout 55 to 68% SiO less than 5% 130:, from about 7 to 10% CaO, fromabout 2 to 5% MgO, from about 11 to 14% alkali metal oxides, a minoramount of A1 0 and between about 3.5 and 4.5% (TiO -l-ZrO- allpercentages being by weight, the CaO, MgO, S10 and A1 0 having suchproportions in the composition that the weight ratio MgO/CaO liesbetween about 0.3 and 0.5, the weight ratio. CaO/SiO is less than about0.16, and the sum of the percentages of SiO;;, B 0 and A1 0 lies betweenabout 67 and 72.

9. A glass composition consisting essentially of the following: fromabout 55 to 68% SiO less than 5% 13 0 from about 7 to 10% CaO, fromabout 2 to 5% MgO, from about 11 to 14% alkali metal oxides, a minoramount of A1 0 and between about 4.0 and 4.2% (TiO +ZrO all percentagesbeing by weight, the CaO, MgO, SiO and A1 0 having such proportions inthe composition that the weight ratio MgO/CaO lies between about 0.3 and0.5, the weight ratio CaO/SiO- is less than about 0.16, and the sum ofthe percentages of SiO B 0 and A1 0 lies between about 67 and 72.

10. A glass composition consisting essentially of the following: fromabout 55 to 66% SiO from about 3 to 5% B 0 from about 3 to 9% A1 0 fromabout 7 to 9.5% CaO, from about 2.8 to 4.5% MgO, and from about 11.5 to14% alkaline metal oxides, all percentages being by weight.

11. A glass composition consisting esesntially of the following: fromabout 55 to 66% SiO from about 3 to 5% E 0 from about 3 to 9% A1 0 lessthan 6% Fe O from about 7 to 9.5% CaO, from about 2.8 to 4.5% MgO, lessthan 3% BaO, from about 11.5 to 14% (Na' O-l-K O), less than 4% F, andfrom about 3.5

Fe O from about 7 to 9.5% CaO, from about 2.8 to

4.5% MgO, less than 3% BaO, from about 11.5 to 14% (Na O+K O), and lessthan 4% F, all percentages being by weight.

14. A glass composition consisting essentially of the following: fromabout 55 to 66% SiO from about 4.3 to 4.6% B 0 from about 3.5 to 5% Al Ofrom about 9 to 9.5% CaO, from about 3.7 to 4% MgO, from about 1 to 2%BaO, and from about 11.5 to 13% (N21 C-1- K 'O), all percentagcs beingby weight.

15. A glass composition consisting essentially of the following: fromabout 55 to 66% SiO from about 4.3 to 4.6% B 0 from about 3.5 to 5% A1 0less than about 1% Fe O from about 9 to 9.5% CaO, from about 3.7 to 4%MgO, from about 1 to 2% BaO, from about 11.510 13% (Na- O-l-K O) andless than about 3% F, all percentages being by weight.

16. A glass composition consisting essentially of the following: fromabout 55 to 66% SiO from about 3 to 5% B 0 from about 3.5 to 5% A1 0from about 9 to 9.5% CaO, from about 3.7 to 4% MgO, from aboutl to 2%BaO, from about 11.5 to 13% (Na O-1- K 0), and from about 3.5 to 4.5%(ZrO +TiO all percentages being by weight.

17. A glass composition consisting essentially of the following: fromabout 55 to 66% S10 from about 3 to 5% B 0 from about 3.5 to 5% A1 0less than about 1% .Fe O from about 9 to 9.5% CaO, from about 3.7 to 4%MgO, from about 1 to 2% BaO, from about 11.5 to 13% (Na O+K O), not morethan about 3% F, and from about 3.5 to 4.5% (ZrO +TiO all percentagesbeing by weight.

18. A glass composition consisting essentially of the following: fromabout 55 to 68% SiO from about 3 to 9% A1 0 from about 7 to 10% CaO,from about 2 to 5% MgO, from about 11 to 14% (Na O+K O+ Li O), from asmall but effective amount to 5% E 0 from 0 to 4.5% (ZrO +TiO from 04%BaO, and from 0 to 12% Fe O all percentages being by weight.

19. A glass composition as defined in claim 21, wherein the weight ratioof CaO to SiO is less than .16.

20. A glass composition consisting essentially of the following:

Percent by weight 1 SiO,, 55 to 68 A1 0 3 to 9 CaO 7 to 9.5 MgO 2.8 to4.5 (Na O-l-K' O) 11.5 to 14 B203 3 t0 5 (ZrO -l-TiO 0 to 4.5- BaO 0 to3 21. Glass composition as defined in claim 20 wherein the weight ratioof CaO to SiO is less than .16.

' 22. A glass composition as defined in claim 21 com- 23. A glasscomposition consisting essentially of the following: from about 55 to66% SiO less than 5% B from about 7 to 10% CaO, from about 2 to MgO,from about 11 to 14% alkali metal oxides, ZrO and TiO totaling less than5%, and a minor amount of A1 0 all percentages being by weight, the SiOB 0 CaO, MgO, A1 0 ZrO and TiO- having such proportions in thecomposition that the weight ratio MgO/CaO lies between about 0.3 and0.5, the weight ratio CaO/SiO is less than about 0.16, the sum of thepercentages of SiO T103, and ZrO lies between about 5' 55 and 68, andthe sum of the percentages of SiO:, TiO

ZrO B 0 and Al O lies between about 67 and 72.

24. A glass composition consisting essentially of the following: fromabout 55 to 66% SiO from about 7 to 10% CaO, from about 2 to 5% MgO,from about 11 to 14% alkali metal oxides, ZrO and TiO totaling betweenabout 2.5% and 3.5%, and a minor amount of Al O all percentages being byweight, the SiO CaO, MgO, A1 0 ZrO and TiO having such proportions inthe composition that the weight ratio MgO/CaO lies between about 0.3 and0.5, the weight ratio CaO/SiO is less than about 0.16, the sum of thepercentages of SiO TiO and ZrO lies between about 55 and 68, and

the sum of the percentages of S10 T10 ZrO and A1303 lies between about67 and 72.

25. A glass composition consisting essentially of the following: fromabout 55 to 66% SiO from about 0.5 to 5% (ZrO +TiO from about 3 to 9% AlO from about 7 to 9.5% CaO, from about 2.8 to 4.5% MgO, and from about11.5 to 14% alkali'metal oxides, all precentages being by weight.

26. A glass composition consisting essentially of the following: fromabout 55 to 66% SiO from about 2.5 to 3.3% (ZrO- +TiO from about 3 to 9%A1 0 from about 7 to 9.5% CaO, from about 2.8 to 4.5% MgO, from about 1to 2% BaO, and from about 11.5 to 14% (Na O+K O), all percentages beingby weight.

' 27. As an article of manufacture, glass fibers having the followingcomposition in percent by weight:

s10 554s BaO 0-5 13,0 e o-s ZrOfi-TiO, o-s F8320 0-6 C80 7-10 MgO v 2-5Na O+K O 11-14 0-4 28. Glass fibers in accordance with claim 27, inwhich the Al O content lies between 3 and 9% by weight.

29. As an article of manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% SiO,, from about 3 to 5% B 0from about 3 to essentially the following composition: from about to 89% A1 0 less than 6% H2 0 from about 7 to 9.5% CaO, from about 2.8 to4.5% MgO, less than 3% BaO, from about 11.5 to 14% (Na O+K O), less than4% F, and from about 3.5 to 4.5% (Zro -l-TiO all percentages being byweight.

31. As an article of manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% SiO from about 3 to 5% B 0from about 3 to 9% Al O from about 7 to 9.5% CaO, from about 2.8 to 4.5%MgO, and from about 11.5 to l4% Na;O-l-K O), all percentages being byweight.

32. As an article of manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% SiO- from about 4.3 to 4.6%B 0 from about 3.5 to 5% A1 0 from about-9 to 9.5% CaO, from about -3.7to 4% MgO, from about 1 to 2% BaO, and from about 11.5 to 13% (Na OlKO), all percentages being by weight.

33. As an article of manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% SiO from about 3 to 5% 13 0from about 3.5 to 5% A1 0 from about 9 to 9.5% CaO, from about 3.7 to 4%MgO, from about 1 to 2% BaO, from about 11.5 to 13% (Na O+K O), and fromabout 3.5 to 4.5% (ZrO +TiO all percentages being by weight.

34. As an article of manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% SiO less than 5% B 0 fromabout 7 to 10% CaO, from about 2 to to 5% MgO, from about 11 to 14%alkali metal oxides, ZrO and TiO totaling less than 5%, and a minoramount of Al o all percentages being by weight, the SiO B 0 CaO, MgO, AlO and T10 having such proportions in the composition that the weightratio MgO/CaO lies between about 0.3 and 0.5, the weight ratio CaO/SiOis less than about 0.16, the sum of the percentages of SiO;, TiO, andZrO; lies between about 55 and 68, and the sum of the percentages ofSiO;, TiO ZrO B 0 and A1303 lies between about 67 and 72.

35. As an article of manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% SiO from about 0.5 to 5%(ZrO +TiO from about 3 to 9% A1 0 less than 6% Fe O from about 7 to 9.5%CaO, from about 2.8 to 4.5% MgO, less than 5% BaO, from about 11.5 to14% (Na,O|K O), and less than 4% F, all percentages being by weight.

36. As an article of manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% $102, from about 2.5 to 3.3%zro,+'rio, from about 3 to 9% A1 0 less than 6% Fe O from about 7 to9.5% CaO, from about 2.8 to 4.5% MgO, from about 1 to 2% BaO, from about11.5 to 14% (Na 0+ K 0), and less than 3% F, all percentages being byweight.

37. As an articleof manufacture, glass fibers having essentially thefollowing composition: from about 55 to 66% SiO from about 0.5 to 3.5%(ZrO +TiO from about 6.8 to 8.3% A1 0 from about 4 to 6% Fe O from about7 to 8% CaO, from about 3.5 to 4.5% MgO, less than 2% BaO, from about11.5 to 14% (Na O+'K,O), less than 3% F, all percentages being byweight.

References Cited in the file of this patent I UNITED STATES PATENTS2,443,142 Lyle June 8. 1948 2,640,784 Tiedc et al. June 2, 19532,664,359 Dingledy Dec. 29, 1953 2,756,158 Hahn et al. July 24, 1956FOREIGN PATENTS 1,137,393. France May 28, 1957 OTHER REFERENCESGlastechnische Tabellen, Eitel-Pirani-Scheel, 1932 ed., pages 661-663.

1 UNITED STATES PATENT OFFICE CERTIFICATE OF CURRECTION Patent No. 3Ol3,888 December 19 1961 Stphane dc Lajarte It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 41-, 1ine 61, for "MgO2-5" read Ca0-7-1O column 6, line 21, for"41.3" road 3 to 3 co1umn 8,'

line 10 for "14% Na O+K 0)" road 14% (Na 0+1 0) Line 29, strike out"to", second occurrence; line 3311 for "A1 0 read A1 0 line 42, after"S110 insert a comma.

ti 1 I o Signed and sea1ed this 1st day of May 1962.

g (SEAL) Attest:

i ERNEST W. SWIDER DAVID L; LADD g Attesting Officer Commissioner ofPatents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIG? Patent No;3 Ol3 888 Decembe l9 1961 Stephaue de Lajarte It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 4, line l fer "Mg()--2=-5 read Ca0--71O column 6, line 2l, for4.3" read 3 to '--3 column 8, line l0 for "l4% NQ Q K OD" read 14% (Ne QK O) 5 line 29, strike out "to"" second occurrence; line 31L, for Al qread A1 0 line 4 2 after 5110 insert a comma.

Signed and sealeclthis lst day of May 1962.,

(SEAL) Attcst: 4

ERNEST w. SWIDER DAVID L. LADD Attesting Officer 7 Commissioner ofPatents

27. AS AN ARTICLE OF MANUFACTURE, GLASS FIBERS HAVING THE FOLLOWINGCOMPOSITION IN PERCENT BY WEIGHT: